Elastic Relaxation and Structure of Liquids. I. Ultrasonic Absorption in Some Halogenated Methylenes, Ethanes, and Ethylenes

In order to obtain information on the presence of structural effects in the elastic relaxation phenomena observed in liquids, the ultrasonic absorption was studied as a function of temperature in some organic compounds whose structure is correlated in a simple way. Large differences of absorption coefficient and of its temperature dependence have been found. It is difficult, at the present time, to understand clearly the results, but they show that the liquid structure has a great importance in the relaxation phenomena present in liquids. Moreover an increase in dipole moment of the molecules is often present with an increase of absorption, showing that the dipole moment is not related in a simple way with the characteristics of relaxation phenomena and that all the interactions among the molecules are to be taken in account.